I don't know much about X-Windows. Sometimes I run a remote X-windows session to an HP DL380 host from my MacBook Pro on the same LAN. I'm using X11 forwarding with the ssh -X option. The X-Windows performance is kind of slow. How can I speed this up? Can I install a video card in the HP DL380 to speed up performance? Is there another way?

From all that I understand about X, a better/newer video card shouldn't make remote rendering better, but I am hoping someone can chime in with more info, great question.
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TimJan 24 '12 at 21:20

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The location of the server when it comes to X is counterintuitive to some people. For clarity, specify in your question which machine you want to install the card on: the machine running the program(s) or the machine with the display, keyboard, and mouse.
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JdeBPJan 24 '12 at 21:23

From what I understand, the application will run on the remote host but the X-Windows server will run on the local host, which in this case is the MacBook Pro.
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Nathan FarringtonJan 25 '12 at 1:15

VNC is not an X11 accelerator. It's a completely different protocol which basically amounts to a continuously-updated screenshot.
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WyzardJan 25 '12 at 6:01

Here as a presentation comparing X, VNC, and NX. The performance of VNC and NX is about the same. X "should" perform very well over a LAN too based on these reported RTT measurements. But you are right, the best way to speed up X is to use NX or VNC. Thanks!
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Nathan FarringtonJan 25 '12 at 8:21

Short answer, No, X is a brain dead protocol. Why X isn't dead by now is astonishing. (I had high hopes for display postscript but that went nowhere...). In X-windows the "Server" is your Mac. The client is the application you are running. X tells your Mac what to render and the Mac does all the work on drawing the screen. At best it's possible that should it be possible to get a better card for your Mac, you might increase performance- but not by much. X "accelerators" like NX work by compressing and caching X calls (essentially replacing X with a better protocol)

I use an Ubuntu server as a work-horse for my calculations and connect from my desktop-pc with ssh to the server. For some applications (gnuplot =) this is really slow altough it’s over LAN. I found on the internet some instructions to improve this situation: instead of the AES cipher the arcfour and blowfish ciphers perform much better and switching on compression also doesn’t hurt. Therefore one should use

ssh -c arcfour,blowfish-cbc -XC host.com

to connect to with ssh. And guess what? This really improves the situation, especially for gnuplot. Thanks Samat!